Snap switch



P. G. FRERER Aug, 30, 1949.

SNAP SWITCH Filed July 28. 1944 Maw m m E V m ATTORNEYS Patented Aug. 30, 1949 2,480,127 SNAP swrrcn Paul Gr Frerer, Milwaukee, Wis, asslgnor to Perfex Corporation, Milwaukee, Wis, a corporation of Wisconsin Application July 28, 1944, Serial No. 547,019 I invention relates to switching mechanism,

and more particularly to self-contained enclosed snap switch units.

The primary object of this invention is to provide a simple and dependable enclosed snap switch which requires a minimum amount of power to operate.

A further object of the invention is the provision of an enclosed snap switch mechanism with suitable adjustments so that such units may be .produced in quantity with uniformity in action.

A further object of the invention is to provide a snap switch unit of the plunger actuated type in which a relatively slight pressure on the plunger actuates the switch.

It is highly desirable that snap switch units be manufactured in which uniformity is maintained in the position of the plunger which causes operation of the switch. This variation in certain applications, such as automatic control instruments, requires that each instrument be calibrated for the particular switch it happens to have. is required, the instrument must be recalibrated. if all of the switches are uniform in the plunger position which causes switch actuation, then the switches are readily replaceable, requiring no recalibration.

A further object of the present invention is to provide an enclosed snap switch construction in which the position of the plunger causing actuation may be readily adjusted, thereby providing for uniformity of this characteristic in production.

Other objects of the invention will appear from the following description and the appended claims.

For a full disclosure of the invention reference is made to the following detailed description and to the accompanying drawings, in which,

Fig. 1 is a top view of a snap switch embodying the invention, with the cover removed;

Fig. 2 is a side view partly in section showing the internal construction of the switch mechanism;

Fig. 3 is a bottom view of the switch housing showing the wiring terminals; and

Fig. 4 is a. fragmentary view similar to Fig. 2, but showing a modified form of mounting for the switch blade.

Referring to the drawings, reference character i indicates the base member of the switching unit. This base member may be of molded plastic and is hollowed out on its upper faceas at 2.

Thus if the switch fails and replacement 8 Claims. (Cl. 200-67) 3 which is formed with a boss 4 which receives a plunger 5. This plunger 5 is provided with an enlarged head 6 and is urged upwardly by means of a leaf spring member 'i.- This leaf spring member is formed with an off-set and is secured by means of screws 8 and 9 to a shoulder which is formed on the upper face of the base I.

The mid-portion of the leaf spring member l is riveted to an elongated switch operating arm ID by means of rivets ll. Also secured to the spring blade I by rivets I l is a contact spring blade I2 which carries a movable contact l3 at its free' end. Preferably the switch arm I0 is formed with a keyhole type slot M (Fig. 1) for ease in assembling. Thus in assembling the switch the contact I3 is first secured to the spring 'blade l2. Then the contact I3 is passed through the enlarged portion of the keyhole slot I l and then slipped into place. The diameter of contact I3 is greater than the width of the narrow portion of keyhole slot it. Thus the bottom of contact l3 serves as a stop for switch arm ill.

The movable contact I3 cooperates with a stationary contact It. This stationary contact faces the base and is formed on a contact stud I'l. This contact stud is carried by a bracket l8 which is preferably staked to a terminal bushing 20 which is molded in the base I. The bracket l8 may be further secured to the base by the inclusion of a horizontal extension M which receives screws 22 and 23 which extend through the base. The bracket is is provided with an upstanding portion 25 which is located adjacent one side of the switch housing (Fig. 1). This upstanding portion of the bracket [8 supports a horizontally extending ear 26 to which the contact stud ii is secured. The bracket it also includes an inwardly and vertically extending ear 21 which supports a permanent magnet 28. This magnet is held in place by means of a non-magnetic washer 29 and a screw 30. It will be noted that the switch operating arm ll) extends on beyond the contact E3 to a point adjacent the pole pieces of the magnet, the end of this arm serving as an armature.

Also located in the base is a second terminal bushing 32 having terminal screw 33 for the attachment of an electrical conductor. This terminal bushing is electrically connected with the fixed end of the spring hinge member 1 by means of a conductor bracket 34. It will be observed that when the contacts i3 and I6 are engaged an electrical circuit is completed from the terminal 32, through conductor 34, spring hinge I,

The base member is formed to receive a cover ont c blade Contact 3, contact stud l1 and bracket l8 to the terminal 20. The head portion 6 of the switch actuating plunger is preferably formed of insulating material so that the plunger 5 is completely insulated from the electrical circuit passing through the switch.

With the parts in the positions shown, the plunger 5 is in its outermost position and the permanent magnet 28 has attracted the armature l and this has forced the movable contact l3 into engagement with the stationary contact IS. The electrical circuit through the switch is therefore completed. When pressure is applied to the plunger 5 this urges the free end of the leaf spring 1 downwardly against a set screw 36 which is threaded in the switch arm ID. This applies a downward force to the switch arm, thereby tending to rock the switch arm I0 downwardly against the pull of the magnet. As the plunger 5 is continued to be depressed, the tension of the leaf spring member will gradually be increased until a point is reached at which the holding force of the magnet is overcome. The switch arm Ill will now be forced downwardly by means of the tension stored up in the spring 1, thereby pulling the movable contact 13 from the fixed contact l6. Asthe plunger is allowed to move upwardly the attractive force of the magnet 28 on the armature member It will maintain the spring 1 against the head of plunger 5. Finally a point will be reached at which the attractive force of the armature will overcome the tension of the spring 1 and the switch arm Ill will snap upwardly for again closing the contacts.

It will be noted that the stationary contact ill forms a stop which limits the upward movement of the armature ill. Therefore, by adjusting the contact stud H, the distance between the armature and magnet may be set when the contacts are closed. This distance varies the amount of tension that must be stored up in spring l before the contacts disengage. Thus adjustment of the contact stud il provides for setting or determining the initial pressure on plunger 5 which is necessary to open the switch. This contact stud H is preferably adjusted with the cover and the plunger in place. This adjustment may be made by inserting a wrench through the hole 37 which is formed in the cover in alignment with the stud ll. After this adjustment is made either another cover may be substituted or the hole 37 may be filled with a suitable filler.

It is highly desirable to provide means for adjusting the position of the plunger 5 which causes actuation of the switch. Such an adjustment provides for insuring that each switch manufactured will have the same distance between the end of the plunger (when in switch actuating position) and the mounting of the switch. In the embodiment of the invention illustrated, this critical distance, designated X, is the distance between the outer end of the plunger when in switch actuating position (note the dotted line showing of the upper end of the plunger appearing in Fig. 2) and the axis of the mounting holes 38 in the base. It will be observed that if this distance is exactly the same for all switches, then one switch may be readily substituted for another switch in a given instrument without in any way affecting the remainder of the instrument.

The purpose of the set screw 36 is to provide a positive adjustment for this distance so as to wrench may be inserted through the bushing for adjusting the set screw 86. It will be observed that adjustment of the set screw 36 varies the tension on the spring I. Thus the screw may be adjusted so as to provide the necessary tension in spring 1 for opening the switch with the plunger 5 in the predetermined position. After this adjustment is made, the terminal screw 33 is put in place and thus there is no opening left in the switch housing.

Fig. 4 shows an alternative arrangement for anchoring the fixed end of the spring hinge I. In this revised construction the spring hinge I is secured to a bracket 40 which is in turn secured to the terminal bushing 32. The base is formed with an opening 4| which receives a set screw which is threaded in a plate 43. The bracket 40 is originally formed so as to always bear against the set screw 42. It will be noted that adjustment of the set screw 42 will tilt the free end of the bracket All and thus tilt the fixed end of the spring hinge I. By this arrangement the spring hinge 1 may be lined up so that it is exerting substantially no force in either direction. This arrangement makes it possible for the manufacturing tolerances of the various parts to be quite wide, while still obtaining the necessary precision in assembly for proper operation of the blade I, armature member or arm in, and resilient blade i2, are rigidly united as by means of rivets H to form a unitary spring hinge assembly or structure which can be readily bodily mounted on or removed from the base 2 or from the bracket ill thereon simply by inserting or removing the fastening means designated screws 8 and 9 in Fig. 2. This feature is or particular importance in that it greatly simplifies the manufacture and assembly of the switch parts, and in that it affords ready access to parts requiring removal for the purpose of servicing and/or replacing same.

It will be noted that the switch mechanism of the present invention is simple in construction and employs a minimum of parts. This novel construction due to its simplicity reduces the friction losses in the switch to a minimum and therefore provides a highly sensitive switch construction which requires a very small amount of power to operate. It will be further seen that due to the novel adjustments provided, each switch after assembly may be readily calibrated to meet a certain standard. Thus each switch may be calibrated so that it opens with a certain force applied to plunger 5. Also each switch may be further calibrated after assembly so as to maintain a certain predetermined distance between the end of the plunger in switch actuating position and the mounting of the switch. These adjustments provide for wider tolerances in manufacture, thereby lowering the cost of the switches in production. Also, these adjustments provide for insuring that each switch is uniform and thereby replaceable with another switch of the same type.

While I have shown and described a specific and preferred embodiment of the invention, it is obvious that many modifications which are within the scope of the invention may occur to those skilled in the art. It is therefore desired to be limited only by the scope of the appended claims.

What is claimed is: 1

1. An enclosed snap switch comprising an elon gated base, a pair of terminals on one side of the base, a stationary contact on the other side of the base and carried by the base, said stationary contact being spaced from the base and facing the base, a permanent magnet carried by the base and spaced therefrom, said permanent masnet having pole pieces facingthe base, an elongated arm extending parallel with the base and connected to the other of said terminals, said elongated arm extending between the base and permanent magnet and having an armature portion adjacent said permanent magnet, a movable contact cooperating with said stationary contact and actuated by said arm, a cover carried by the base, a plunger extending through the cover for actuating said arm, a leaf spring interposed between the plunger and arm, a set screw between the leaf spring and arm for adjusting the relationship therebetween, said set screw being located in alignment with one of said terminals and adapted to be adjusted by a tool inserted through said last mentioned terminal.

2. An enclosed snap switch unit comprising a base, a pair of terminals mounted on one side of the base, one of said terminals being formed to receive a terminal screw, the hole for the screw extending through the base, a stationary contact on the other side of the base and electrically connected to one of said terminals, a movable contact arranged to cooperate with said stationmy contact and electrically connected to the other of said terminals, a cover carried by the base. means extending through said cover for actuating said movable contact, snap action means for imparting snap action motion to said movable contact, a set screw for adjusting the snap switch unit, said set screw being located in alignment with said terminal screw hole so that it may beadjusted by a tool inserted through said screw hole.

3. An enclosed snap switch unit comprising a base, a pair of terminals mounted on one side of the base, one of said terminals being formed to receive a terminal screw, the hole for the screw extending through the base, a stationar contact on the other side of the base and electrically connected to one of said terminals, a movable contact arranged to cooperate with said stationmy contact and electrically connected to the other of said terminals, a pivoted switch actuating arm for actuating said movable contact, snap action means for imparting snap action motion to said arm and including a leaf spring attached to said arm, a cover for the snap switch unit, a plunger extending through the cover for actuating said leaf spring, and a set screw interposed between said leaf spring and arm for adlusting the position of the plunger at which the arm is actuated with snap action, said set screw the tension of said spring hinge for a given position of said switch arm.

5. In a switching mechanism, a base, a stationary contact mounted on said base, a unitary spring hinge assembly detachably secured to said base at a point remote from said stationary contact, said spring hinge assembly including a contact spring blade extending toward and to a point in proximity to said stationary contact, an elongated relatively rigid switch operating arm extending longitudinally of said blade in spaced generally parallel relation with respect to the contact opposing end thereof, and including a leaf spring member extending longitudinall of said blade and terminating short of said stationary contact in a free end portion spaced from said blade, an actuating means bearing against a portion of said leaf spring member spaced from said blade, and a tension adjusting set screw extending through said blade and arm with its inner end opposing said leaf spring member.

6. In a switching mechanism, a base, a switch operating arm, a spring hinge having one portion fixedly clamped to said base and having another portion spaced from said one portion and fixedly secured to said switch am, said spring hinge having an offset portion extending longitudinally of said switch arm in spaced relation thereto, a, set screw carried by said switch operating arm in a position to bear against said offset portion for adjusting position of the latter relative to the former, and an actuating means for the switch arm bearing against said offset portion.

'1. An enclosed snap switch comprising a readily separable base and cover, a pair of terminals on the outer side of said base, one of said terminals being formed to receive a terminal screw with the hole for said screw extending through said base, a stationary contact electrically connected with the other one of said terminals and mounted from the inner side of said base, a permanent magnet carried by said base and presenting a pair of armature engaging pole faces disposed adjacent to said contact, an elongated slotted switch operating arm having an armature end opposite said pole face and having its other end electrically connected with said one of said terminals and mounted for oscillation hingedly from the inner side of said base at a point remote from said stationary contact and pole faces, a contact spring blade secured to the switch arm at a point adjacent its hinge mounting and extending substantially parallel to said arm between said arm and said base to a point opposite said stationary contact and short of said pole faces, a leaf spring member secured to the base --and to the switch actuating arm to provide for being in alignment with said terminal screw hole so that it may be adjusted by a tool inserted through said screw hole.

4. In a switching mechanism, a base, an offset bracket having one portion secured to the base and another portion spaced therefrom, a spring hinge attached to said other portion of the bracket and being thereb secured to the base, a switch arm fixedly secured to a portion of said spring hinge at a point adjacent said bracket and being thereby pivotally supported for movement relative to said base, snap action means associated with said switch arm, an actuator for actuating said switch arm to cause the same to move with snap action. and adjusting means coacting with said bracket and base for rocking said other portion of the bracket relative to said one portion and relative to said base for thereby adjusting the hinged movement thereof, said leaf spring member being disposed parallel to said switch actuating arm in spaced relation to its side opposite the contact spring blade and terminating short of said stationary contact in a free end portion, a contact carried by said contact spring blade and extending loosely through the slot in the switch operating arm with an enlarged head to contact the stationary contact, a plunger movably mounted on said cover and engaging said free end of the leaf spring member for actuating the hinge movement of the switch operating arm to disengage the movable contact and move the armature end of said arm from the pole faces, and a set screw extending through said switch operating arm with one end of said set screw opposing the leaf spring member and its other end aligned with said terminal screw hole whereby said screw'is positioned for adjustment by a tool inserted through said hole.

8. In a snap switch, a spring hinge assembly provided with a movable contact; a housing and base providing a fixed contact, magnet. and a mounting for said assembly; an actuator to move said assembly hingedly to make and break said contacts, said assembly having a leaf spring member offset outwardly therefrom and to contact with said actuator; and an adjusting set screw between the assembly and said leaf spring member whereby to adjust the setting of the snap action with respect to the movement of the actuator against said leaf spring.

PAUL G. FRERER. 15

nmnucns orrnn The following references are of record-in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,862,631 Penn June 14, 1932 2,170,341 Shaw Aug. 22, 1939 2,202,681 Allen May 28, 1940 2,261,016 Carlson Oct. 28, 1941 2,327,069 'Satterlee Aug. 17, 1943 2,385,887 Shaw Oct. 2, 1945 

